While attempting to answer a question for someone on the platform-dev list today, I wanted to reference the document Jesse Glick wrote entitled "NetBeans To Thread or Not To Thread" about threading in NetBeans.  Doing a Google search shows it to be posted here:

   http://core.netbeans.org/proposals/threading/

but following that URL yields an error, I assume because the URL for that has changed somehow without updating content that links to those URLs.

I've encountered several other similar errors in the past few weeks, but did not report them because I assumed they were temporary.  Here are a few more examples so you'll see the extent of the problem:

This formerly valid address to Jaroslav Tulach's "Test Patterns in Java" is now broken:

    http://openide.netbeans.org/tutorial/test-patterns.html

As is the NetBeans Versioning Policy:

    http://openide.netbeans.org/versioning-policy.html

and the documentation about Window System design:

    http://core.netbeans.org/windowsystem/

I see a pattern that leads me to believe that all content on <site>.netbeans.org, where <site> is a non-empty string other than 'www', is now gone.  However, the documentation about JellyTools (functional testing library for NetBeans Platform applications):

    http://netbeans.org/projects/jellytools/docs.html

is now gone too, so perhaps this is an even bigger problem than it seems.